(i) Field of the Invention
The present invention relates to a cooling device for the drive system of an automotive vehicle, and more particularly to an improvement in the cooling performance of an air cooling device for use in the belt drive system of an all terrain vehicle, which employes a drive system of belt-driving type.
(ii) Description of the Prior Art
In a relatively light-weight automotive vehicle of specific type adapted in particular to the so-called all-terrain operation, a power transmission system of belt drive type is commonly employed as its drive. This belt-type transmission is generally of such construction that the belt drive mechanism is enclosed fully by a covering or casing for the purpose of protecting the entire drive mechanism from any possible splashing of muddy water or intrusion of dust or other foreign matter, otherwise they may enter into the drive mechanism casing. By the way, from such a fully enclosed structure of the drive mechanism, it is inevitably that a driving V-belt and pulleys incorporated in the drive mechanism which are fully enclosed in the casing may well be subjected to a hazardous effect of heating from the friction driving operation of such members involved. In coping with such an undesired heating effect, it is essential to employ a certain means of cooling-off the resulting heat in these driving members, particularly the drive belt which is rather less resistant to the effect of heat. For this purpose, there have been proposed a variety of cooling means in particular for the belt drive mechanism, such as a forced draft system which is designed to have outside air introduced forcedly into the casing or the belt chamber.
As a typical example of such a forced draft cooling system, such a construction is generally known that there are provided an air inlet and an outlet in the front and rear ends of the casing of the belt drive mechanism, respectively, and a suction fan built integrally with a drive pulley is adapted to have outside air introduced into the casing of the drive mechanism through the air inlet, while letting hot air existing within the belt chamber out thereof through the outlet.
On the other hand, referring further to the general construction of such cooling device, it is known that the configurations of the air inlet and outlet provided in the casing of drive mechanism is getting more complicated in an attempt to hamper possible entrance of dirty water or the like through these inlet and outlet structure in the casing. Particularly, in the operation of the all-terrain vehicle, it is very possible that such air inlet and outlet might come under the level of water while running through shallows and muddy lands. In consideration of such a possible operating condition, it is the common practice in the design of such draft system that there is provided a certain length of piping extending upwardly from the air inlet and outlet portions for the protection of the belt drive mechanism within the enclosure from the intrusion of foreign matter into the casing. With such construction, it is naturally inevitable that there is produced a substantial resistance against the passage of cooling air to be introduced into the casing for vent, thus making it impracticable that the effect of suction generated from the suction fan may eventually satisfy the requirement of cooling upon the V-belt and the like members involved in the drive mechanism of the vehicle, after all.
In consideration of such drawbacks particular to the conventional construction of air cooling systems for use with the belt drive mechanism for an all-terrain vehicle as noted above, it would be desirable to attain an efficient resolution for overcoming such inevitable problems particalur to the conventional construction.
The present invention is essentially directed to the provision of a due and proper resolution to such inconveniences and difficulties in practice as outlined above and experienced in the conventional air cooling systems which have been left unattended with any proper countermeasures therefor.